A combinational weighing apparatus generally used for automatically weighing, for example, various articles is provided with a plurality of weighing hoppers and is so configured as to perform a weighing of the articles which have been dispersedly supplied onto those weighing hoppers, as to perform a combinational calculatiion based on the weights measured by those weighing hoppers, as to subsequently determine a combination of combined sums which may fall within a permissible range with respect to a target weight, and as to discharge the articles only from one of the weighing hoppers which has given the combination so that an aggregation of the articles of a total weight falling within the permissible range. This type of weighing appratus may have a pool hopper disposed immediately above each of the weighing hoppers so that when the articles to be weighed are discharged from the weighing hoppers, articles to be weighed, which participate in the subsequent combination, can be immediately discharged from the pool hoppers onto the weighing hoppers.
As indicated above, this type of weighing apparatus is provided with a plurality of hoppers and, in such case, a hopper generally called a gated-type hopper is employed for each hopper. This gated-type hopper comprises, for example, a hopper body having a top opening upwardly and a bottom formed with a discharge port, and a gate for selectively opening and closing the discharge port at said bottom and is so configured that articles to be weighed which have been supplied through the top opening of the hopper body can be discharged from the bottom discharge port by selectively opening and closing the gate.
The selective opening and closure of the gate in the gated-type hopper of the type discussed above has hitherto been carried out by operating a link member fitted unitarily on the side of the hopper. In other words, the Japanese Examined Utility Model Publication No. 7-6502, for example, discloses the structure comprising a motor as a drive source, a cam mounted on a rotary shaft of the motor, an operating lever protruding outwardly from a side surface of the body of the weighing apparatus and drivingly associated with rotation of the cam so as to undergo a rocking motion, all provided on the side of the weighing apparatus, and a link member provided on the side of the hopper and connected with a gate. This hopper is fitted to the body of the weighing apparatus with the operating lever engaged with the link member so that the link member can be operated in response to the rocking motion of the operating lever to thereby selectively open and close the gate of the hopper. Also, the Japanese Laid-open Utility Model Publication No. 6-58328, for example, discloses the structure in which there is provided a push rod capable of being selectively advanced and retracted from the side of the body of the weighing apparatus so that a link member provided on the side of the hopper and connected with the gate can be operated by this push rod to selectively open and close the gate.
However, in those prior art weighing apparatuses, although the drive motor and the operating lever or the push rod are provided on the side of the weighing apparatus, the link member operated by the operating lever or the push rod to selectively open and close the gate and a spring for biasing the gate towards a closed position are provided on the side of the hopper. Therefore, there have been problems in that not only does the entire structure of the hopper tend to become complicated, requiring time-consuming jobs of a routine inspection, a routine cleaning or detaching and mounting of the hopper to the body of the weighing apparatus, but also the number of component parts is increased accompanied by possible separation or loss of small component parts such as screws and the biasing spring. Also, where the structure is employed in which neither the link member nor the spring member is provided on the side of the hopper, the necessity of use of a lock means has arisen to lock the gate in the closed position so that the gate will not open during closure of the gate by the effect of the weight of the articles to be weighed that have been supplied to the hopper.
The present invention has been devised to substantially eliminate the above discussed problems and is intended to provide a weighing apparatus wherein the structure of the hopper is simplified to thereby improve the workability in detachment relative to the body of the weighing apparatus, the maintenance and the cleanliness, and wherein a mechanism for inhibiting the opening of the gate during closure of the gate is realized in a drive device on the side of the body of the weighing apparatus with a simple structure.